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Topic: Fixing up an old dividing head (Read 5386 times)

This is a dividing head I bought at auction several years ago. It came with a 3 jaw chuck and a tailstock. It weighs about 70 lbs with the chuck, and I believe it is a 10" head. It doesn't have division plates or an indexer, but I figured I could make those.

When I rubbed some of the grime and surface rust away I was able to make out -- in very small letters -- the manufacturer's name. It was Kempsmith.

It's rather large for my Enco mill drill, but a working dividing head would be better to have than no dividing head. So before I get rid of the electrolytic de-rusting bath I used on my mill vice, I thought I'd dunk this one. I could use it to make a 48 tooth change gear for my lathe -- that one is missing from my set.

I'm really glad to be fixing this up -- it has been sitting on the shelf for years in my house just asking to be worked on. When I first bought it at auction I didn't even own a mill.

The auction was at an old pump manufacturing site, now out of business. Might have been a Hayward Tyler plant -- but I don't remember for sure. Seemed like it must have been closed for a decade from the looks of it.

They had pattern making facilities, lots of screw making machines, etc. I snagged a barrel of bronze and brass scrap and another of aluminum in the screw machine room together for $75. Several hundredweight. This dividing head with the chuck and tailstock went for $50. I also bought a cast iron surface plate and cast iron straightedge for $25 each. I was basically out of money at that point and saw much more important stuff go all day long. Quite exhiirating to be there and just wander through the place, making bids sometimes I knew would lose. But wow!

Anyway got this one apart as far as I could. It was kind of like a Chinese puzzle -- I'm still not sure how they got this thing together beyond the point I got to.

After some searching online, I finally found a manual for a Kempsmith dividing head. Very interesting reading showing among other things, how it is used in a driven mode on a horizontal mill to cut spirals -- worms, threads, etc. This is one rugged unit! It also shows how they test them at the factory and the tolerances required. Great booklet!

The publication date is 1916, but I think mine is similar but even earlier -- it's simpler, has 90 degree indexing shaft, not angled upwards, and doesn't have a quick release lever. I wonder how old this really is?

I tried to upload the manual here as an attachment, but it exceeds the 10 mb limit for the pdf. file.

I was hoping that the 6" 3 jaw chuck might have the same thread pattern as my Atlas lathe. It took about 20 minutes to free it from the dividing head. But no such luck. A much finer thread on the Kempsmith.

There was achip out of the dial face for rotating the position of the dividing head -- right at the index mark. I also noticed that the bearing block that holds the worm shaft had two cracks in it. Probably caused by the same accident. You can see it in the photo below.

I don't think this will affect anything, the block is quite large and the crack is only at the end surface, but I was reluctant to try to press the bearing housing out because of it. I decided to strip the rust on the main block without disassembling further.

I decided not to paint the main body at this point because I am afraid paint will seep down into the joint between the barrel and the main body casting. Since I wasn't able to take the dividing head fully apart, I can't mask these parts separately. I'll just have to keep it well oiled and protected.

It is still very stiff if I try to rotate the body -- but it should loosen up over time with use and once the lubrication has a chance to penetrate everywhere. Paint could make that worse. It took quite a while to rotate the chuck end upright, as it finally is here. I wanted to put it in this position so I can use it to drill its own dividing plates.

The worm and wheel work well -- they were a little stiff, but cleaning and lubricating, and then working them some loosened them up. There is provision to adjust backlash in this dividing head.

Dsquire I have a feeling I won't be using it to its full capacity on my mill drill! Amazing though what it was expected to do. I always thought of dividing heads as somewhat delicate. Driving a spindle is heavy work.

StillDrillin, do you have any pics of your old mill?

I've been re reading my old Gingery book on building a dividing head -- I think I will use it as a model for making the indexing pin, sector arms and fraction plates for the Kempsmith. The plates on the Gingery head were 5-3/4" -- just about right for this one, I figure. Plates can't be too big or they will interfere with clearance to the mill head when in certain positions.

I figure about half the swing capacity of the dividing head -- so in this case that would be right. Since Gingery has detailed out all of th other parts, it should be a fairly easy adaptation.